Epidemiologic studies are conducted to identify life-style and environmental risk factors for cancer and to investigate their interrelationships with genetic determinants of these diseases. Case-control studies of cancers of the bladder, prostate, pancreas, esophagus, stomach, lung, brain, and head and neck, as well as non-Hodgkins lymphoma and multiple myeloma, are in progress. A large case-control study of bladder cancer is progressing in Spain to identify occupational bladder carcinogens and to evaluate non-occupational exposures including cigarette smoking (black vs. blond tobacco), phenacetin-containing analgesics, dietary factors, and urination frequency and pH. Genetic susceptibility markers also will be evaluated in relation to bladder cancer risk, as well as their interaction with epidemiologic risk factors. Studies of participants in a large screening trialfor prostat, lung, colorectal, and ovarian cancer (PLCO Trial) showed reduced risk for colorectal adenoma in relation to high dietary fiber intake and reduced risks for benign prostatic enlargement in relation to greater alcohol intake. A large case-control study of bladder cancer in New England is underway to determine the reasons for the persistently elevated bladder cancer mortality and incidence in the northeastern United States. Results of a case-control study of pancreatic cancer conducted at three U.S. centers suggested that heavy use of smokeless tobacco, and to a lesser extent, cigar smoking, may increase the risk of pancreatic cancer among nonsomkers of cigaretts. In Puerto Rico, results of a population-based case-control study of oral cancer suggested that alcohol concentration is a risk factor for oral cancer independent of the total quantity of alcohol consumed. Risks associated with combined exposure to tobacco were also more pronounced when subjects drank liquor straight. In Shanghai, a multi-center case-control study of colon cancer indicated that increased physical activity, particularly commuting physical activity is associated with a reduced risk of colon cancer. Furthermore, the effect of physical activity is independant of body mass index. In another study, risk of a number of cancer, including colon, pancreatic, and esophageal, is increased among obese veterans. Findings from a multi-center case-control study of prostate cancer in American blacks and whites suggested that greater height may be associated with better survival from prostate cancer.